Replacing the function and appearance of the human foot has long been a goal of prosthetists, engineers, and others involved in the rehabilitation of amputees. Since the 1950s and the introduction of the SACH foot, numerous organizations and individuals have applied the sciences of materials, engineering, biomechanics, and human movement to design innovative prosthetic feet and ankles. Recently, new prosthetic feet designs and enhancements have been introduced at a near dizzying pace. Many features are offered such as energy storage and release, accommodation to all sorts of terrain, powered components, and enhanced appeal through natural appearance, color variations, and even adjustable heel height. Behind these developments are scientists, engineers, manufacturers, and entrepreneurs who often do their own testing or may put their products through rigorous standardized engineering tests of strength, function, and durability. Others, such as prosthetists, physicians, therapists, and biomechanists, have attempted to study, classify, or compare feet through gait labs, energy consumption tests, perceptive analysis questionnaires, or functional outcome measures.